Saliva Can Help Diagnose Heart Attack, Study Shows

Early diagnosis of a heart attack may now be possible using only a few drops of saliva and a new nano-bio-chip, a multi-institutional team led by researchers at The University of Texas at Austin reported at a recent meeting of the American Association for Dental Research.

The nano-bio-chip assay could some day be used to analyze a patient's saliva on board an ambulance, at the dentist's office or at a neighborhood drugstore, helping save lives and prevent damage from cardiac disease. The device is the size of a credit card and can produce results in as little as 15 minutes.

Nano-bio-chips like this one made of silicon (in blue) can be used to test saliva for characteristics of heart disease. The round objects in back are nano-bio-chips microfabricated from sheets of stainless steel, making them about 100 times cheaper than silicon. Photo by Glen Simmons.

"Many heart attack victims, especially women, experience nonspecific symptoms and secure medical help too late after permanent damage to the cardiac tissue has occurred," says John T. McDevitt, principal investigator and designer of the nano-bio-chip. "Our tests promise to dramatically improve the accuracy and speed of cardiac diagnosis."

McDevitt, a professor of chemistry and biochemistry at The University of Texas at Austin, collaborated with scientists and clinicians at the University of Kentucky, University of Louisville, and The University of Texas Health Science Center at San Antonio.

Cardiovascular disease is the leading cause of death in developed countries, including the United States. In 2008, an estimated 770,000 Americans will have a new coronary attack, and about 430,000 will have a recurrent attack.

"There is certainly a strong need for more effective early diagnosis of cardiac disease," says McDevitt.

McDevitt and his co-workers and collaborators took advantage of the recent identification of a number of blood serum proteins that are significant contributors to, and thus indicators of, cardiac disease.

Leveraging microelectronics components and microfabrication developed initially for the electronic industry, the research group developed a series of compact nano-bio-chip sensor devices that are biochemically-programmed to detect sets of these proteins in saliva. They looked at 32 proteins currently used for diagnosis of blood serum in cardiac clinical practice.

The new diagnostic test works like this: A patient spits into a tube and the saliva is then transferred to a credit card-sized lab card that holds the nano-bio-chip. The loaded card is inserted like an ATM card into an analyzer that manipulates the sample and analyses the patient's cardiac status on the spot.

The test can reveal that a patient is currently having a heart attack and that they should receive treatment quickly. It can also tell a patient that they are at high risk of having a future heart attack.

The researchers have currently measured 80 clinical patients and their data shows that the saliva tests were nearly equivalent to more standard tests on blood serum using FDA-approved instruments.

"What's novel here is our ability to measure all such proteins in one setting and to use a noninvasive saliva sample, where low protein levels make such tests difficult even with large and expensive lab instruments," McDevitt says.

The new technology is still in the clinical testing phase, but it is a strong candidate for further commercial development through the Austin, Texas company LabNow, Inc., a start-up venture that licensed the lab-on-a-chip technologies from The University of Texas at Austin. LabNow's first lab-on-a-chip product, now in development, targets HIV immune function testing and can be used in resource poor settings like Africa.

Lead investigators from The University of Texas at Austin are Drs. John McDevitt, Nicolaos Christodoulides and Pierre N. Floriano. The University of Texas Health Science Center at San Antonio lead investigators include Drs. Chih-Ko Yeh and Spencer Redding. Lead investigators at the University of Kentucky are Drs. Craig Miller, Michael J. Novak and Jeff Ebersole. University of Louisville lead investigator is Dr. Denis Kinane.

This research is supported by the National Institute of Dental and Craniofacial Research at the National Institutes of Health.